The present invention relates generally to capacitance probes for measuring magnetic recording head transducer to disc surface spacing. More particularly, the present invention is directed toward a capacitance probe fabricated by patterning a capacitance plate over a transducer element on a slider body such that the air bearing surface (ABS) characteristics are preserved.
Disc drive data storage systems utilize read/write transducers contained within a slider body (typically collectively referred to as a read/write head) which "flies" above a rotating magnetic storage disc. In the production of disc drive data storage systems, it is useful to make non-contact measurements of the distance between a magnetic disc surface and the read/write head (i.e., the fly height). Further, it is useful to map the overall disc topography using such fly height measurements. Accurate measurements of the spacing between the read/write head and the disc surface is a necessity in any hard disc drive design to verify the head-to-disc interface functionality for mechanical, tribological and electrical performances.
Fly height testers using light interferometry principles have been utilized for years. However, such devices can only be used with a transparent glass disc and can only perform the fly height measurement with the head in a static flying position. Further, these devices cannot measure the gap spacing at the transducer. Therefore, transducer spacing estimates are often obtained by extrapolation and can be inaccurate due to surface curvature existing in the ABS of the slider body.
Also in the prior art, capacitance probe fly height testers have been used in which the entire slider body of the read/write head acts as a first capacitance plate, with the disc surface acting as the second capacitance plate. Between the two capacitance plates, a fly height indicating capacitance can be measured. However, using the entire slider body as a capacitance plate does not provide information needed to determine the roll characteristics of the slider. This configuration can only measure gross average slider-to-disc surface spacing and will not provide transducer gap spacing values.
Other prior art designs have moved away from the problems associated with using the entire slider body as a capacitance plate by implanting capacitance probes in the slider body, typically at the ABS. However, this requires modification to the slider body which disturbs the ABS and changes the mass and inertial characteristics of the head. Further, with smaller read/write heads, the implanted probe designs are extremely difficult to manufacture and result in very low yields.
Consequently, there is a need for an improved capacitance probe, which overcomes these and other limitations of prior art capacitance probes, so that changes in fly height during dynamic operations such as track seek, actuator slam, latch impact and ramp load/unload can be accurately measured in-situ in a disc drive or at a component level on the actual magnetic storage media being used.